Jake LaMotta, a k a the Raging Bull, teams with longtime girlfriend Denise Baker for a mortifying off-Broadway show.Michael Weintraub

Jake LaMotta may be 90, but he can still beat Mike Tyson to the punch.

The legendary pugilist has opened his autobiographical show, “Lady and the Champ,” just before Tyson hits Broadway next Tuesday. And while Tyson isn’t encouraging any press, the Raging Bull had the guts to invite the critics.

That may not have been a good idea, since this ramshackle evening of songs and stories co-starring his “lady” — longtime girlfriend Denise Baker — has an uncomfortable air of exploitation. It seems mostly designed to satisfy the showbiz aspirations of Baker, who once appeared in the erotic musical “Let My People Come.”

The show, at the pocket-size Richmond Shepard Theatre, provides fans the opportunity to get close to one of the greatest middleweight fighters of all time. But the elderly champ is hardly seen to his advantage. Wearing a Stetson and sitting motionless at a small table, he’s interviewed by a nerdy male “journalist” who cues him into delivering halting commentary about his life and boxing career, especially his famed bouts with Sugar Ray Robinson.

LaMotta displays his old spark while describing such things as his style of “rolling with the punches,” but he’s no comedian. It’s painful to hear him reciting corny jokes about his troubled personal life: “My first wife died from eating mushrooms. My second wife died from eating mushrooms. My third wife died of a skull fracture. She refused to eat the mushrooms.”

Other cringeworthy moments include his delivery of Brando’s “I coulda been a contender” speech from “On the Waterfront” and a recitation of the lyrics from “My Way.”

But those embarrassments pale alongside Baker’s over-the-top renditions of “New York, New York,” “The Boxer” and a rewritten “Can’t Help Falling in Love” that would make Bill Murray’s lounge-lizard singer squirm.

At the show’s end, LaMotta regales the crowd with a bit of shadowboxing, showing he’s still got the moves. Thrilling as it is, it’s not enough to compensate for the sheer mortification preceding it.